A new method for visualising chromosomes is painting a truer picture of their shape, which is rarely like the X-shaped blob of DNA most of us are familiar with.

Scientists at the BBSRC-funded Babraham Institute, working with the University of Cambridge and the Weizmann Institute, have produced beautiful 3D models that more accurately show their complex shape and the way DNA within them folds up.

The X-shape, often used to describe chromosomes, is only a snapshot of their complexity.

"The image of a chromosome, an X-shaped blob of DNA, is familiar to many but this microscopic portrait of a chromosome actually shows a structure that occurs only transiently in cells – at a point when they are just about to divide."

"The vast majority of cells in an organism have finished dividing and their chromosomes don't look anything like the X-shape. Chromosomes in these cells exist in a very different form and so far it has been impossible to create accurate pictures of their structure."

Peter's team has developed a new method to visualise their shape. It involves creating thousands of molecular measurements of chromosomes in single cells, using the latest DNA sequencing technology. By combining these tiny measurements, using powerful computers, they have created a three-dimensional portrait of chromosomes for the first time. This new technology has been made possible thanks to funding from the Biotechnology and Biological Sciences Research Council (BBSRC), Medical Research Council (MRC) and the Wellcome Trust.

Dr Fraser added:

"These unique images not only show us the structure of the chromosome, but also the path of the DNA in it, allowing us to map specific genes and other important features. Using these 3D models, we have begun to unravel the basic principles of chromosome structure and its role in how our genome functions."

This latest research, published in Nature, puts DNA into its proper context in a cell, conveying the beauty and complexity of the mammalian genome in a far more effective way than volumes of text previously have. In doing so it shows that the structure of these chromosomes, and the way the DNA within them folds up, are intimately linked to when and how much genes are expressed, which has direct consequences for health, ageing and disease.

Douglas Kell, BBSRC Chief Executive, said:

"Until now, our understanding of chromosome structure has been limited to rather fuzzy pictures, alongside diagrams of the all too familiar X-shape seen before cell division. These truer pictures help us to understand more about what chromosomes look like in the majority of cells in our bodies. The intricate folds help to unravel how chromosomes interact and how genome functions are controlled."

A research team led by Professor Jun Takahashi and Assistant Professor Asuka Morizane at the Center for iPS Cell Research and Application (CiRA) at Kyoto University, Japan, has carried out a study to compare the impact of immune response in autologous transplantation (transplantation of cells from the subject's own body) and allogeneic transplantation (transplantation of cells from a different individual of the same species). The researchers used cynomolgus monkeys to carry out transplantation into the brain of neural cells derived from iPS cells. Autologous transplantation was found to produce almost no immune reaction and to result in viable neural cells. By contrast, allogeneic transplantation provoked immune reaction by microglia and lymphocytes.

Parkinson's disease is a progressive and intractable disease of the nervous system in which the loss of dopaminergic neurons in the brain leads to reduced dopamine production, resulting in limb tremor, stiffness causing difficulty in movement, and other symptoms. The therapies applied up till now, based on drugs or electrode treatment, may improve symptoms but have proved unable to halt the depletion of dopaminergic neurons. Hopes have therefore become focused on a therapy with the more radical approach of replacing the lost neural cells through cell transplantation, thereby promoting the formation of new neural pathways to restore brain function. Human iPS cells are looked to as a potential source of the transplant cells.

This is an immunostaining of primate
iPSC-

derived neurons on day 39. Green colors
shows

dopaminergic neural cells. Credit: Courtesy
of

Dr. Asuka Morizane.

It is hoped that iPS cells will make it possible to use cells derived from the transplant patients themselves to perform autologous transplantation. If autologous transplantation could allow immune reaction to be avoided, it would also make unnecessary the use of immunosuppressant drugs and avert the risk of side-effects caused by immunosuppression. However, the studies of iPS cell-based autologous transplantation carried out so far, which have used a mouse model, have produced no firm conclusion, with immune reaction observed in some studies but not in others. Moreover, these studies did not involve transplantation of differentiated cells derived from iPS cells in a way that mimicked clinical application. There had thus been no studies directly investigating the effect of autologous transplantation and allogeneic transplantation in primates. This study by Dr. Takahashi's group sought to clarify this area by transplanting dopaminergic neurons prepared from iPS cells into the brains of cynomolgus monkeys and comparing the extent of immune reaction between autologous and allogeneic transplantation.

iPS cells prepared from four cynomolgus monkeys were differentiated into dopaminergic neural cells over a period of 28 days and transplanted into the monkeys' brains, which were observed over a period of approximately three months during which no immunosuppressant were used. The study data show that, in primates, autologous transplantation of iPS cell-derived neural cells produces almost no immune reaction and is superior to allogeneic transplantation in terms of immune reaction control and cell viability.

Wednesday, 18 September 2013

Weizmann Institute scientists show that removing 1 protein from adult cells enables them to efficiently turn back the clock to a stem-cell-like state

Wednesday, 18 September 2013

This is
Dr. Yaqub Hanna. Credit: Weizmann

Institute of Science.

Embryonic stem cells have the enormous potential to treat and cure many medical problems. That is why the discovery that induced embryonic-like stem cells can be created from skin cells (iPS cells) was rewarded with a Nobel Prize in 2012. But the process has remained frustratingly slow and inefficient, and the resulting stem cells are not yet ready for medical use. Research in the lab of the Weizmann Institute's Dr. Yaqub Hanna, which appears today in Nature, dramatically changes that. He and his group revealed the "brake" that holds back the production of stem cells, and found that releasing this brake can both synchronize the process and increase its efficiency from around 1% or less today to 100%. These findings may help facilitate the production of stem cells for medical use, as well as advancing our understanding of the mysterious process by which adult cells can revert back into their original, embryonic state.

Embryonic stem cells are those that have not undergone any "specialization"; thus they can give rise to any type of cell in the body. This is what makes them so valuable: They can be used, among other things, to repair damaged tissue, treat autoimmune disease and even grow transplant organs. Using stem cells taken from embryos is problematic because of availability and ethical concerns, but the hopes for their use were renewed in 2006, when a team led by Shinya Yamanaka of Kyoto University discovered that it is possible to "reprogram" adult cells. The resulting cells, called "induced pluripotent stem cells" (iPSCs), are created by inserting four genes into their DNA. Despite this breakthrough, the reprograming process is fraught with difficulty: It can take up to four weeks; the timing is not coordinated among the cells; and less than one percent of the treated cells actually end up becoming stem cells.

Hanna and his team asked: What is the main obstacle – or obstacles – that prevent successful reprograming in the majority of cells? In his postdoctoral research, Hanna had employed mathematical models to show that a single obstacle was responsible. Of course in biology, Hanna is the first to admit, experimental proof is required to back up the models. The present study not only provides the proof, it reveals the identity of that single obstacle and shows that removing it can dramatically improve reprograming.

Left
column: This is the previous method

for
creating induced pluripotent stem cells

(iPSCs);
right column: These are iPSCs

produced
with the new method developed

by Dr.
Hanna. Top: Skin cells (red); center:

iPSCs
from skin cells (green); bottom: super-

imposed
top and center images. Skin cells

that
have been reprogrammed into iPSCs

appear
light yellow. Only a small percentage

of the
cells on the left have been

reprogrammed,
in contrast with the high

success
rate seen with the new method on

the
right. Credit: Weizmann Institute of

Science.

Hanna's group, led by Dr. Noa Novershtern, Yoach Rais, Asaf Zviran and Shay Geula of the Molecular Genetics Department, together with members of the genomics unit of the Institute's Israel Structural Proteomics Center, looked at a certain protein, called MBD3, whose function was unknown. MBD3 had caught their attention because it is expressed in every cell in the body, at every stage of development. This is quite rare: In general, most types of proteins are produced in specific cells, at specific times, for specific functions. The team found that there is one exception to the rule of universal expression of this protein: the first three days after conception. These are exactly the three days in which the fertilized egg begins dividing, and the nascent embryo is a growing ball of pluripotent stem cells that will eventually supply all the cell types in the body. Starting on the fourth day, differentiation begins and the cells already start to lose their pluripotent status. And that is just when the MBD3 proteins first appear.

This finding has significant implications for the producing iPSCs for medical use. Yamanaka used viruses to insert the four genes but, for safety reasons, these are not used in reprograming cells to be used in patients. This gives the process an even lower success rate of only around a tenth of a percent. The researchers showed that removing MBD3 from the adult cells can improve efficiency and speed the process by several orders of magnitude. The time needed to produce the stem cells was shortened from four weeks to eight days. As an added bonus, since the cells all underwent the reprograming at the same rate, the scientists will now be able, for the first time, to actually follow it step by step and reveal its mechanisms of operation. Hanna points out that his team's achievement was based on research into the natural pathways of embryonic development.

"Scientists investigating reprograming can benefit from a deeper understanding of how embryonic stem cells are produced in nature. After all, nature still makes them best, in the most efficient manner."

A duo of scientists at Penn State University has achieved a major milestone in understanding how genomic "dark matter" originates. This "dark matter" – called non-coding RNA – does not contain the blueprint for making proteins and yet it comprises more than 95 percent of the human genome. The researchers have discovered that essentially all coding and non-coding RNA originates at the same types of locations along the human genome. The team's findings eventually may help to pinpoint exactly where complex-disease traits reside, since the genetic origins of many diseases reside outside of the coding region of the genome.

A duo of scientists at Penn State
University has

achieved a major milestone in
understanding

genomic "dark matter" --
called non-coding RNA.

This "dark matter" is
difficult to detect and no

one knows exactly what it is doing or
why it is

there in our genome, but scientists
suspect it may

be the source of inherited diseases.
This research

achievement may help to pinpoint
exactly where

complex-disease traits reside in the
human

genome. This illustration shows, in the
upper left

corner, a chromosome – a densely
compressed

package containing one long, continuous
strand

of DNA. The DNA is pervasively
transcribed into

RNA, but only a very small fraction of
the RNA

has the instructions (or codes) for
making proteins.

The green circles in this illustration
represent places

along the strand of DNA where
transcription

originates. New research led by B.
Franklin Pugh

of Penn State University shows that
essentially all

RNA, whether or not it codes for
proteins, originates

at the same types of locations along
the strand

of DNA. The findings eventually may
help to

pinpoint exactly where complex-disease
traits

reside, since the genetic origins of
many diseases

reside outside of the coding region of
the genome.

Credit: National
Institutes of Health and B.

Franklin Pugh, Penn State University.

The research, which will be published as an Advance Online Publication in the journal Nature, was performed by B. Franklin Pugh, holder of the William chair in Molecular Biology at Penn State, and postdoctoral scholar Bryan Venters, who now holds a faculty position at Vanderbilt University.

In their research, Pugh and Venters set out to identify the precise location of the beginnings of transcription – the first step in the expression of genes into proteins.

"During transcription, DNA is copied into RNA – the single-stranded genetic material that is thought to have preceded the appearance of DNA on Earth – by an enzyme called RNA polymerase and, after several more steps, genes are encoded and proteins eventually are produced," Pugh explained.

He added that, in their quest to learn just where transcription begins, other scientists had looked directly at RNA. However, Pugh and Venters instead determined where along human chromosomes the proteins that initiate transcription of the non-coding RNA were located.

"We took this approach because so many RNAs are rapidly destroyed soon after they are made, and this makes them hard to detect," Pugh said.

"So rather than look for the RNA product of transcription we looked for the 'initiation machine' that makes the RNA. This machine assembles RNA polymerase, which goes on to make RNA, which goes on to make a protein."

Pugh added that he and Venters were stunned to find 160,000 of these "initiation machines," because humans only have about 30,000 genes.

"This finding is even more remarkable, given that fewer than 10,000 of these machines actually were found right at the site of genes. Since most genes are turned off in cells, it is understandable why they are typically devoid of the initiation machinery."

The remaining 150,000 initiation machines – those Pugh and Venters did not find right at genes – remained somewhat mysterious.

"These initiation machines that were not associated with genes were clearly active since they were making RNA and aligned with fragments of RNA discovered by other scientists," Pugh said.

"In the early days, these fragments of RNA were generally dismissed as irrelevant since they did not code for proteins."

Pugh added that it was easy to dismiss these fragments because they lacked a feature called polyadenylation – a long string of genetic material, adenosine bases – that protect the RNA from being destroyed. Pugh and Venters further validated their surprising findings by determining that these non-coding initiation machines recognized the same DNA sequences as the ones at coding genes, indicating that they have a specific origin and that their production is regulated, just like it is at coding genes.

"These non-coding RNAs have been called the 'dark matter' of the genome because, just like the dark matter of the universe, they are massive in terms of coverage – making up over 95 percent of the human genome. However, they are difficult to detect and no one knows exactly what they all are doing or why they are there," Pugh said.

"Now at least we know that they are real, and not just 'noise' or 'junk.' Of course, the next step is to answer the question, 'what, in fact, do they do?'"

Pugh added that the implications of this research could represent one step towards solving the problem of "missing heritability" – a concept that describes how most traits, including many diseases, cannot be accounted for by individual genes and seem to have their origins in regions of the genome that do not code for proteins.

"It is difficult to pin down the source of a disease when the mutation maps to a region of the genome with no known function," Pugh said.

"However, if such regions produce RNA then we are one step closer to understanding that disease."

System can help discern recipes for tissue and organ repair and replacements

Wednesday, 18 September 2013

Scientists know that physical and biochemical signals can guide cells to make, for example, muscle, blood vessels or bone. But the exact recipes to produce the desired tissues have proved elusive.

Now, researchers at Case Western Reserve University have taken a step toward identifying that mix by developing an easy and versatile way of forming physical and biochemical gradients in three dimensions.

Ultimately, one of their goals is to engineer systems to manipulate stem cells to repair or replace damaged tissues and organs.

"If we can control the spatial presentation of signals, we may be able to have more control over cell behaviour and enhance the rate and quality of tissue formation," said Eben Alsberg, an associate professor of biomedical engineering and orthopaedic surgery at Case Western Reserve and senior author of the research.

"Many tissues form during development and healing processes at least in part due to gradients of signals: gradients of growth factors, gradients of physical triggers."

Alsberg, postdoctoral scholar Oju Jeon and graduate student Daniel S. Alt of Case Western Reserve, and Stephen W. Linderman, a visiting undergraduate on a National Science Foundation Research Experience for Undergraduates summer fellowship, tested their system on mesenchymal stem cells, turning them toward bone or cartilage cells. They report their findings in Advanced Materials.

Regulating the presentation of certain signals in three-dimensional space may be a key to engineering complex tissues, such as repairing osteochondral defects, damaged cartilage and bone in osteoarthritic joints, Alsberg said.

"There must be a transition from bone to cartilage," he said, "and that may require control over multiple signals to induce the stem cells to change into the different kinds of cells to form tissues where you need them."

In their first test, the researchers found that stem cells changed into cartilage or bone cells in the directions of two opposing soluble growth factor gradients: one that promotes cartilage, called TGF-beta 1, and another that promotes bone, called BMP-2. The stem cells were placed in a solution of modified alginate, a material derived from seaweed that can form a jelly-like material called a hydrogel when exposed to low level ultraviolet light.

The solution was divided between two computer-controlled syringe pumps, with BMP-2 in one syringe and TGF-beta 1 in the other. By controlling the rate of injection with the pumps and using a mixing unit, a hydrogel with a BMP-2 gradient starting with a large amount and tapering to nearly none and an opposing TGF-beta 1 gradient from low-to-high was formed.

The hydrogels were further modified in such a way that the growth factors were retained for a longer period of time. This enabled prolonged exposure of stem cells to the growth factors and further control over their differentiation into bone or cartilage cells.

The researchers then modified the hydrogel with a gradient of adhesion ligands, molecular strings that allow the stem cells to attach to the hydrogel itself. After two weeks of culturing the cells, they found the highest number of cells in the hydrogel region where the concentration of ligands was highest.

In a third test, they created a gradient of crosslink density within the hydrogels. Crosslinks provide structure to the gels. The lower the density, the more flexible the hydrogel; the higher, the stiffer the gel will become.

After two weeks, more cells were found in the most flexible gel regions within the gradient. The flexibility may allow for more free movement of nutrients and removal of waste products, Alsberg explained.

"This is exciting," Alsberg said.

"We can look at this work as a proof of principle. Using this approach, you can use any growth factor or any adhesion ligand that influences cell behaviour and study the role of gradient presentation. We can also examine multiple different parameters in one system to investigate the role of these gradients in combination on cell behaviour."

If the technology enables them to unravel recipes that generate complex tissues, the biodegradable hydrogel mix could be implanted or injected at the site of an injury, the researchers say. The recipe would guide cell behaviour until new tissue is formed, restoring function.

Tuesday, 17 September 2013

Scientists have succeeded in growing stem cells that have the ability to develop into two different types of cells that make up a healthy pancreas. The research team led by Dr. Hans Clevers of the Hubrecht Institute, The Netherlands, have isolated and grown stem cells from the pancreases of mice using a 3-D culture system previously developed by the scientists. The results, which are reported in The EMBO Journal, could eventually lead to ways to repair damaged insulin-producing b-cells or pancreatic duct cells.

Cell signalling molecules known as Wnts and a protein called Lgr5 are essential to produce adult stem cells that can be coaxed to grow and divide rapidly. However, these signalling pathways and molecules are inactive in the adult pancreas.

"We have found a way to activate the Wnt pathway to produce an unlimited expansion of pancreatic stem cells isolated from mice," Clevers said.

"By changing the growth conditions we can select two different fates for the stem cells and generate large numbers of either hormone-producing b-cells or pancreatic duct cells."

"This work is still at a very early stage and further experiments are needed before we can use such an approach for the culture of human cells but the results are a promising proof-of-concept," he added.

In the study, the pancreases of mice were altered in a way that makes duct cells proliferate and differentiate. Some cells in this new population were stem cells that were capable of self-renewal. The scientists were able to culture these cells to give rise to large numbers of pancreatic cells or tiny clumps of tissue referred to as organoids.

Therapeutic strategies for pancreatic disease have been hampered by a lack of cell culture systems that allow scientists to grow replacement tissue in a test tube or on a dish. Alternative approaches such as tissue transplantation are limited by the scarcity of donors and the possibility of tissue rejection. The new work offers access to an unlimited supply of pancreatic stem cells that would be beneficial for the development of new therapeutic interventions for pancreatic diseases like diabetes.

The next steps for the scientists will include further refinement of the cell culture methods developed in this study and investigation of ways to extend the approach to human pancreatic cells.

Thursday, 12 September 2013

Study reveals network of genes that safeguard cooperation in stem cells and the developing embryo

Thursday, 12 September 2013

We often think of human cells as tiny computers that perform assigned tasks, where disease is a result of a malfunction. But in the current issue of Science, researchers at The Mount Sinai Medical Center offer a radical view of health — seeing it more as a cooperative state among cells, while they see disease as result of cells at war that fight with each other for domination.

Their unique approach is backed by experimental evidence. The researchers show a network of genes in cells, which includes the powerful tumour suppressor p53, which enforce a cooperative state within cells — rather like the queen bee in a beehive. Disease or disorder occurs when these enforcer genes are mutated, allowing competition between cells to ensue.

"Both competition and cooperation drive evolution, and we are wired for cooperation all the way down to our genes," says the study's senior investigator, Thomas P. Zwaka, MD, PhD, Professor at the Black Family Stem Cell Institute at the Icahn School of Medicine at Mount Sinai.

The findings, if backed by future research, offer a new way to address disease, Dr. Zwaka says. Understanding the genetic basis of cooperative and competitive cellular behaviours could explain how cancer and immune system dysfunction develops, he says.

"If a cell has lost a gene that fosters communication among cells, it may dominate other cells by ignoring signals to stop proliferating. It also makes sense that the immune system might detect and attack cells that are not cooperating. Failure to cooperate may also underlie development of birth defects."

He adds that it may be possible to flip the cooperation switch back on therapeutically, or to manipulate stem-like cells to misbehave in a way that produces replacement cells for regenerative medicine.

"Cell misbehave, they are unpredictable. They do not operate like little machines," he says.

"What our study suggests is that cooperation is so central to our evolution that we have genetic mechanisms to protect us against cheating and dominating behaviour."

A network of genes with an ancient function

The research team, which also includes study first author Marion Dejosez, PhD, Assistant Professor at the Icahn School at Mount Sinai, took a long view toward the behaviour of cells. They wondered how it was that cells, which lived on earth as single units for hundreds of millions of years, could effectively bundle themselves together to perform specific tasks.

"Cells started somehow to form alliances, and to cooperate, and obviously this multicellularity had certain advantages."

But they also questioned what happened to the "cheating" behaviour that can be seen in single cells, such as amoeba, that live in colonies — competitive behaviour that allows the cell to gain a reproductive advantage without contributing its fair share to the community.

They conducted a genetic screen in stem cells to look for mutants that allow cells to "misbehave — to become a little antisocial and do things they wouldn't normally do," Dr. Zwaka says.

The screen picked up about 100 genes, which seem to cluster together into a network.

The team focused on three of those genes — p53, long known as the guardian of the genome, Topoisomerase 1 (Top1), which control genomic stability, and olfactory receptors involved in the sensation of smell.

"We could understand that p53 might foster cooperation, because loss of p53 function is a step in the development of many cancers. But finding that top1 and olfactory receptors may have the same function was a surprise," he says.

"We think these genes have the ancient function of safeguarding multicellular organisms by helping cells to coordinate their activities."

The scientists then tested the effects of knocking down these genes in developing mouse embryos. To their surprise, p53 and Top1 knockdown embryos developed normally — perhaps because other intact social enforcement genes took over.

"This showed us that mutant cells only misbehave when they are around normal cells. They become competitive, perhaps promoting an evolutionary advance," Dr. Zwaka says.

"When all the cells are the same, either all mutated or all normal, they cooperate with each other.”

"This study suggests that cell cooperation, altruistic behaviour, cheating, and other so-called social behaviours are wired into cells via the genome at the early primitive stage," he says.

"Perhaps there is no coincidence that amoeba, insects, animals, the human culture and society, generally follow innate rules of cooperation. Darwin's explanation of evolution as a struggle for existence needs to be tempered with an acknowledgment of the importance of cooperation in the evolution of complexity."

Wednesday, 11 September 2013

The characteristics of the obtained stem cells correspond to a primitive totipotent state that has never before been obtained

Wednesday, 11 September 2013

A team from the Spanish National Cancer Research Centre (CNIO) has become the first to make adult cells from a living organism retreat in their evolutionary development to recover the characteristics of embryonic stem cells.

Pictured
are Manuel Serrano and Maria Abad

in his
laboratory at the CNIO. Credit: Spanish

National Cancer Research Center (CNIO).

Researchers have also discovered that these embryonic stem cells, obtained directly from the inside of the organism, have a broader capacity for differentiation than those obtained via in vitro culture. Specifically, they have the characteristics of totipotent cells: a primitive state never before obtained in a laboratory.

The study, carried out by CNIO, was led by Manuel Serrano, the director of the Molecular Oncology Programme and head of the Tumoural Suppression Laboratory. The study was supported by Manuel Manzanares's team from the Spanish National Cardiovascular Research Centre (CNIC).

Embryonic stem cells are the main focus for the future of regenerative medicine. They are the only ones capable of generating any cell type from the hundreds of cell types that make up an adult organism, so they are the first step towards curing illnesses such as Alzheimer, Parkinson's disease or diabetes. Nevertheless, this type of cell has a very short lifespan, limited to the first days of embryonic development, and they do not exist in any part of an adult organism.

One of the greatest achievements in recent biomedical research was in 2006 when Shinya Yamanaka managed to create embryonic stem cells (pluripotent stem cells, induced in vitro or in vitro iPSCs) in a laboratory from adult cells, via a cocktail of just four genes. Yamanaka's discovery, for which he was awarded the Nobel Prize in Medicine in 2012, opened a new horizon in regenerative medicine.

CNIO researchers have taken another step forward, by achieving the same as Yamanaka, but this time within the same organism, in mice, without the need to pass through in vitro culture dishes. Generating these cells within an organism brings this technology even closer to regenerative medicine.

The first challenge for CNIO researchers was to reproduce the Yamanaka experiment in a living being. They chose a mouse as a model organism. Using genetic manipulation techniques, researchers created mice in which Yamanaka's four genes could be activated at will. When these genes were activated, they observed that the adult cells were able to retreat in their evolutionary development to become embryonic stem cells in multiple tissues and organs.

María Abad, the lead author of the article and a researcher in Serrano's group, said:

"This change of direction in development has never been observed in nature. We have demonstrated that we can also obtain embryonic stem cells in adult organisms and not only in the laboratory".

Manuel Serrano added that:

"We can now start to think about methods for inducing regeneration locally and in a transitory manner for a particular damaged tissue".

Stem cells obtained in mice also show totipotent characteristics never generated in a laboratory, equivalent to those present in human embryos at the 72-hour stage of development, when they are composed of just 16 cells.

In comparison with the cells obtained with the technique developed by Yamanaka, the stem cells obtained by CNIO therefore represent an even earlier embryonic state, with greater capacity for differentiation.

The authors were even able to induce the formation of pseudo-embryonic structures (teratomas) in the thoracic and abdominal cavities of the mice. These pseudo-embryos displayed the three layers typical of embryos (ectoderm, mesoderm and endoderm), and extra-embryonic structures such as the Vitelline membrane and even signs of blood cell formation.

"This data tell us that our stem cells are much more versatile than Yamanaka's in vitro iPSCs, whose potency generates the different layers of the embryo but never tissues that sustain the development of a new embryo, like the placenta", said the CNIO researcher.

The authors emphasise that the possible therapeutic applications of their work are still distant, but they admit that, without doubt, it might mean a change of direction for stem cell research, for regenerative medicine or for tissue engineering.

"Our stem cells also survive outside of mice, in a culture, so we can also manipulate them in a laboratory", said Abad.

"The next step is studying if these new stem cells are capable of efficiently generating different tissues such as that of the pancreas, liver or kidney".

Sunday, 8 September 2013

Synthetic mRNA Can Induce Self-repair and Regeneration of the Infarcted Heart

Sunday, 08 September 2013

A team of scientists at Karolinska Institute and Harvard University has taken a major step towards treatment for heart attack, by instructing the injured heart in mice to heal by expressing a factor that triggers cardiovascular regeneration driven by native heart stem cells. The study, published in Nature Biotechnology, also shows that there was an effect on driving the formation of a small number of new cardiac muscle cells.

Dr. Kenneth Chien was recently
recruited as a

researcher to Karolinska Institutet and
now

share his time between Sweden and the
US.

Credit: Ulf
Sirborn.

"This is the beginning of using the heart as a factory to produce growth factors for specific families of cardiovascular stem cells, and suggests that it may be possible to generate new heart parts without delivering any new cells to the heart itself ", says Kenneth Chien, a Professor at the medical university Karolinska Institute in Sweden and Harvard University, US, who led the research team behind the new findings.

The study is based upon another recent discovery in the Chien lab, which was published in Cell Research. This study shows that VEGFA, a known growth factor for vascular endothelial cells in the adult heart, can also serve as a switch that converts heart stem cells away from becoming cardiac muscle and towards the formation of the coronary vessels in the fetal heart. To coax the heart to make the VEGFA, the investigators in the Nature Biotechnology study used new technology where synthetic messenger RNA (mRNA) that encodes VEGFA is injected into the muscle cell. Then, heart muscle produces a short pulse of VEGFA. The mRNA is synthetically modified so that it escapes the normal defense system of the body that is known to reject and degrade the non-modified mRNA as a viral invader.

The study, performed in mice, shows that only a single administration of a short pulse of expression of VEGFA is required, if it can be delivered to the exact region where the heart progenitors reside. The therapeutic effect is long term, as shown by markedly improved survival following myocardial infarction with a single administration of the synthetic mRNA when given within 48 hours after the heart attack. The long-term effect appears to be based on changing the fate of the native heart stem cells from contributing to cardiac fibrotic scar tissue and towards cardiovascular tissue.

"This moves us very close to clinical studies to regenerate cardiovascular tissue with a single chemical agent without the need for injecting any additional cells into the heart," says Professor Chien.

At the same time, he points out that these are still early days and there remains much to be done. In particular, it will become of interest to engineer new device technology to deliver the synthetic mRNA via conventional catheter technology. It also will be critical to move these studies, which are based in mouse models, to other animals, which is currently in progress.

It is widely believed that bone marrow mesenchymal stem cells are highly adherent fibroblastic cells, defined as colony-forming unit-fibroblasts. Nevertheless, a few reports have shown that the non-adherent bone marrow cells can give rise to colony-forming unit-fibroblasts in vitro, and possess a certain differentiation potential.

Non-adherent bone marrow cell-derived mesenchymal stem cells from β-galactosidase transgenic mice were also transplanted into focal ischemic brain (right corpus striatum) of C57BL/6J mice. Cells co-labeled with both β-galactosidase and NeuN were seen by double immunohistochemical staining. These findings, published in the Neural Regeneration Research, suggest that the non-adherent bone marrow cell-derived mesenchymal stem cells could differentiate into neuronal-like cells in vitro and in vivo, which can be used as seed cells for the treatment of nervous system diseases.